重载流插入运算符

#include <iostream>

/* run this program using the console pauser or add your own getch, system("pause") or input loop */
using namespace std;
class Complex
{
    public:
        Complex(){
            real=0;
            imag=0;
        }
        Complex(double r,double i){
            real=r;
            imag=i;
        }
        Complex operator +(Complex &c2);
        friend ostream&operator<<(ostream&,Complex&);
    private:
        double real;
        double imag;
 } ;
 
 Complex Complex::operator +(Complex &c2)
 {
     return Complex(real+c2.real,imag+c2.imag);
 }
 
 ostream&operator<<(ostream&output,Complex&c)
 {
     output<<"("<<c.real<<"+"<<c.imag<<"i)"<<endl;
     return output;
 }
 
int main(int argc, char** argv) {
    Complex c1(2,4),c2(6,10),c3;
    c3=c1+c2;
    cout<<c3;
    return 0;
}